For the seventh annual Doodle 4 Google competition, the tech giant asked students, from kindergarten to 12th grade, to draw an invention that would improve the world.

Out of more than 100,000 submissions, Audrey Zhang of New York won. Her invention was a "transformative water purifier."

"It takes in dirty and polluted water from rivers, lakes and even oceans, then massively transforms the water into clean, safe and sanitary water. When humans and animals drink this water, they will live a healthier life," Zhang said, according to Google's doodle blog.

She received a $30,000 college scholarship and $50,000 Google for Education technology grant for her school, Google said. The company donated $20,000 in Zhang's name for clean water for schools in Bangladesh.